An Acute Bout of Whole-Body Vibration Does Not Improve Jumping Performance in Those With Anterior Cruciate Ligament Reconstruction.

CONTEXT: Individuals with anterior cruciate ligament reconstruction (ACLR) often fail to return to their previous level of sport performance. Although multifaceted, this inability to regain preinjury performance may be influenced by impaired plyometric ability attributable to chronic quadriceps dysfunction. Whole-body vibration (WBV) acutely improves quadriceps function and biomechanics after ACLR, but its effects on jumping performance outcomes such as jump height, the reactive strength index (RSI), and knee work and power are unknown. OBJECTIVE: To evaluate the acute effects of WBV on measures of jumping performance in those with ACLR. DESIGN: Crossover study design. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirty-six individuals with primary, unilateral ACLR. INTERVENTION(S): Participants stood on a WBV platform in a mini-squat position while vibration or no vibration (control) was applied during six 60-second bouts with 2 minutes of rest between bouts. MAIN OUTCOME MEASURE(S): Double-leg jumping tasks were completed preintervention and postintervention (WBV or control) and consisted of jumping off a 30-cm box to 2 force plates half the participant's height away. The jumping task required participants to maximally jump vertically upon striking the force plates. RESULTS: Whole-body vibration did not produce significant improvements in any of the study outcomes (ie, jump height, RSI, and knee work and power) in either limb (P = .053-.839). CONCLUSIONS: These results suggest that a single bout of WBV is insufficient for improving jumping performance in individuals with ACLR. As such, using WBV to acutely improve jumping performance post-ACLR is likely not warranted. Future research should evaluate the effects of repeated exposure to WBV in combination with other plyometric interventions on jumping performance.

Reduced Knee Flexion Strength 18 Years After ACL Reconstruction With Hamstring Tendon Versus Patellar Tendon.

BACKGROUND: Bone-patellar tendon-bone (BPTB) and double-looped semitendinosus and gracilis (hamstring) grafts are commonly used for anterior cruciate ligament (ACL) reconstruction. Short-term and midterm studies show little or no differences between the 2 grafts; however, there are only a few long-term studies to compare results between the 2 grafts. PURPOSE: To compare the results after using either BPTB grafts or hamstring tendon grafts 18 years after ACL reconstruction. STUDY DESIGN: Randomized controlled trial; Level of evidence 2. METHODS: A total of 114 patients with ACL rupture between 2001 and 2004 were randomized to reconstruction with either a BPTB graft or a hamstring tendon graft. Patients were operated on at 4 major hospitals. The 18-year follow-up evaluation included anterior knee laxity measured with a KT-1000 arthrometer, defined as the primary outcome, while clinical examination (Lachman and pivot-shift tests), isokinetic testing of muscle strength, patient-reported outcome measures, and an assessment of radiographic osteoarthritis using the Kellgren-Lawrence classification were defined as secondary outcomes. RESULTS: A total of 96 patients (84%, 47 BPTB and 49 hamstring grafts) were available for follow-up, 71 of these for clinical examination. Seven of 96 patients were excluded for ACL revision (n = 5) or knee replacement (n = 2) surgery. In total, 25 patients (10 BPTB and 15 hamstring grafts) had undergone additional surgery other than ACL revision or total knee arthroplasty. There were no significant differences between the groups in terms of anterior laxity test with KT-1000 arthrometer (primary outcome). In secondary outcomes, no significant differences between groups were reported regarding clinical examination, patient-reported outcome scores, or radiographic osteoarthritis (Kellgren-Lawrence grade 2-4 for patellofemoral joint [18 hamstring and 14 BPTB] or tibiofemoral joint [20 hamstring and 19 BPTB]), while isokinetic testing revealed that the hamstring group had a 10.7% reduction in mean peak flexion torque compared with the BPTB group at 60 deg/s (df = 59; P = .011). At 60 deg/s the mean total flexion work in the hamstring group was reduced by 17.2% compared with the BPTB group (df = 59; P = .002). CONCLUSION: The flexion strength in the hamstring group was significantly reduced in the operated knee after 18 years. There were no significant differences between the groups regarding subjective outcomes, patient-reported outcomes, range of motion, clinical and instrumented knee laxity, and the development of osteoarthritis. REGISTRATION: NCT05876013 (ClinicalTrials.gov identifier).

Anterior cruciate ligament reconstruction in the elderly: 5-Year follow-up study.

BACKGROUND: Older adults remain active for longer and continue sports and activities that require rotation on one leg later in life. The rate of anterior cruciate ligament (ACL) tears is therefore increasing in those over 40 years old, with an associated increase in the rate of surgical reconstruction (ACLR), but there is limited literature on its effectiveness. Our aim was to compare the outcomes of elderly patients who have undergone ACLR with those of a younger group of patients. MATERIALS AND METHODS: Patients who underwent ACLR with bone-patella tendon-bone grafting (BPTB) at a level I trauma center between 2015 and 2017 were included in the study with a 5-year follow-up. Patients were divided into 4 groups: below 40 years, 40-49 years, 50-59 years and over 60 years. The graft function was evaluated by the International Knee Documentation Committee (IKDC) Objective Score, the anteroposterior (AP) displacement was measured by arthrometer (KT-1000; MEDMetric) and the Lysholm scale was used for subjective evaluation. RESULTS: 195 patients were included in the final analysis. The IKDC score showed significantly poorer scores in the 50-59 years and over 60 years group than in the younger groups, however in 83 % and 66 % of cases reached normal or nearly normal grades, respectively. A significant difference was found in the knee AP displacement (measured in mm) between the below 40 years group and 50-59 years as well as over 60 years old groups; however, the number of graft failure (laxity >5 mm) and elongation (>3 mm) did not increased in these senior groups. The patient-reported Lysholm scores in the 40-49 years, 50-59 years and 60 years groups was lower than in the below 40 years group, but the average score was "good". CONCLUSIONS: The long-term results of ACL reconstruction in older athletes are comparable to those of younger patients, both in terms of knee function and patient satisfaction. Furthermore, there is no difference in outcomes for older patients over the age of 40 compared to those in their 50 s or even 60 s. There is still insufficient published evidence to define an upper age limit for ACL reconstruction in older athletes.

Crossover effect of knee and ankle joint training on knee mechanics after ACL reconstruction: A randomized controlled trial.

BACKGROUND: Anterior cruciate ligament (ACL) rehabilitation is a common intervention after ACL reconstruction. Since different types of exercise can influence muscle and kinematic parameters in diverse ways, the training order between the knee and ankle joints may also change gait parameters. PURPOSE: This study aimed to investigate whether the training sequence of the knee and ankle joints (knee followed by ankle training or vice-versa) in an ACL reconstruction (ACLR) rehabilitation program has any effects on knee extension and flexion torques. METHODS: Forty-two men (aged 20-30 years) with ACLR participated in this study. They were randomly allocated to receive one of two interventions: (A) knee joint training followed by ankle training or (B) ankle joint training followed by knee training. After five weeks (four weeks of intervention and one-week washout), participants crossed from one group to another for an additional four weeks. Knee extension and flexion torques were assessed during the stance phase of the gait cycle before and after the intervention program. RESULTS: Two-way Mixed-design MANOVA showed that knee extension torque improved significantly in both groups after training (p = 0.001, Cohen's D = 0.65), while the knee flexion torque increased significantly only in group B (p= 0.001, Cohen's D = 0.97). When comparing both groups, patients of group B presented significant improvements in the post-training mean values of all tested variables compared with group A. CONCLUSION: Starting a post-ACLR rehabilitation program with ankle training followed by knee training is better to improve knee flexion and extension torques during the stance phase of the gait cycle than starting the program by training the knee first, followed by the ankle. Future studies using a mixed-gender sample and different types of ACLR operations are necessary to examine whether similar improvements will happen as well as to test their effects on many sports activities.

Development of a novel geometrically-parametric patient-specific finite element model for anterior cruciate ligament reconstruction.

PURPOSE: A personalized model of the knee joint, with adjustable effective geometric parameters for the transplanted autograft diameter in Anterior Cruciate Ligament Reconstruction (ACLR) using the bone-patella-tendon-bone (BPTB) technique, has been developed. The model will assist researchers in understanding how different graft sizes impact a patient's recovery over time. METHODS: The study involved selecting a group of individuals without knee injuries and one patient who had undergone knee surgery. Gait analysis was conducted on the control group and the patient at various time points. A 3D model of the knee joint was created using medical images of the patient. Forces and torques obtained from the gait analysis were applied to the model to perform finite element analysis. RESULTS: The results of the finite element (FE) analysis, along with kinetic data from both groups, indicate that models with diameters of 7.5 mm and 12 mm improved joint motion during follow-up after ACLR. Additionally, a comparison of the stress applied to the ACL model revealed that a 12 mm autograft diameter showed a more favorable trend in patient recovery during the three follow-up intervals after ACL reconstruction surgery. CONCLUSION: The development of a personalized parametric model with adjustable geometric parameters in ACLR, such as the transplanted autograft diameter, as presented in this study, along with FE using the patient's kinetic data, allows for the examination and selection of an appropriate autograft diameter for Patella Tendon grafting. This can help reduce stress on the autograft and prevent damage to other knee joint tissues after ACLR.

Lateral extrarticular tenodesis enhances outcomes in primary anterior cruciate ligament repair with knotless anchor: 24-Month minimum follow up.

BACKGROUND: Previous studies have shown that primary repair of proximal ligament avulsion from the femoral condyle may have reasonable recovery and stability rates after repair. As a result, selecting patients more narrowly and more specifically has been recognized to improve short- and medium-term outcomes. PURPOSE: This study aimed to assess the potential benefits of primary repair for acute anterior cruciate ligament (ACL) tears with a proximal tear and to evaluate the effect of performing lateral extraarticular tenodesis (LET) in addition to primary repair on patient outcomes. STUDY DESIGN: Retrospective cohort study. METHODS: This study was a retrospective cohort study. Thirty-eight patients between the ages of 21 and 40 years who underwent ACL repair surgery within the first 3 weeks after injury due to Sherman type 1 proximal ACL tears were evaluated. Group 1 (n = 18) underwent only primary ACL repair with knotless anchor, while Group 2 (n = 20) had LET with iliotibial band autograft in addition to primary repair. Patients were evaluated using various tests and scoring systems at 6, 12, and 24 months postoperatively. RESULTS: There was no statistically significant difference between the groups in preoperative and postoperative 6- and 12-month visual analog scale (VAS) scores (P >0.05). However, the 24-month VAS score of Group 1 was statistically significantly higher than that of Group 2 (P <0.05). The preoperative International Knee Documentation Committee (IKDC) score of Group 1 was statistically significantly higher than that of Group 2 (p: 0.004; P <0.05). Group 1 had statistically significantly lower IKDC scores at postoperative 6, 12, and 24 months than Group 2. Similarly, Group 1 had statistically significantly lower Single Assessment Numeric Evaluation (SANE) and Tegner-Lysholm scores at postoperative 6, 12, and 24 months than Group 2 (P <0.05). The occurrence rate of Lachman positivity in the preoperative period was 28.6% in Group 1 and 33.3% in Group 2. CONCLUSION: Our study suggests that performing LET with iliotibial band autograft in addition to primary ACL repair may lead to better outcomes in terms of pain relief, knee function, and stability compared with primary ACL repair alone.

Is Visual Reliance Increased in Athletes After ACL Injury? A Scoping Review.

BACKGROUND: Individuals with anterior cruciate ligament (ACL) injury often exhibit visual cognitive deficits during tasks that require neuromuscular control. In this paper, we present evidence of increased visual reliance after ACL injury during a range of clinically applicable cognitive-motor tasks. This information is essential to strengthen the scientific rationale for therapeutic interventions that target maladaptive neuroplasticity and may translate to improved return-to-sport (RTS) outcomes following ACL injury. OBJECTIVES: The objectives of this study are (1) to determine if visual reliance is present during common rehabilitation-based assessments after ACL deficiency (ACL-D) or ACL reconstruction (ACL-R), (2) to describe how visual reliance is assessed during such tasks, and (3) to provide information to help clinicians and patients understand the clinical relevance of cognitive load in the assessment and intervention of visual reliance. DESIGN: Scoping review. LITERATURE SEARCH: We searched MEDLINE, EMBASE, CINAHL, SCOPUS, and PEDro databases. STUDY SELECTION CRITERIA: Only primary studies published in English were included without time limitations. DATA SYNTHESIS: Qualitative analysis of the included studies was performed. RESULTS: We synthesized the results of 23 studies. A total of 7 studies (31%) included patients with ACL-D, 15 studies (65%) included patients with ACL-R, and 1 study (4%) included patients with ACL-D and ACL-R. Evaluation of tasks, task evaluation setting, visual conditions, outcome measures, and presence of increased visual reliance were identified. Most studies investigating patients with ACL-D, contrary to those with ACL-R, exhibited worse postural stability during eyes-closed conditions than uninjured controls. Complete visual obstruction (i.e., eyes closed or blindfolded) was the most frequently reported method to disrupt vision (52%). The addition of a visual-cognitive challenge resulted in significantly worse postural stability in patients with ACL-R compared with controls. CONCLUSIONS: Visual reliance was most commonly assessed during single leg stance with complete visual obstruction. The majority of studies on patients with ACL-D indicate that they exhibit poorer postural stability in eyes-closed conditions when compared with uninjured controls, which suggests increased visual reliance. There is less evidence of visual reliance in patients who have undergone ACL-R compared with those with ACL-D. Adding a visual-cognitive load was found to be more effective in inducing postural stability deficits in individuals who have undergone ACL-R. LEVEL OF EVIDENCE: IV. The protocol was a priori registered on Open Science Framework ( https://osf.io/p4j95/ ).

The effects of heading motion and sex on lower extremity biomechanics in soccer players.

BACKGROUND: Soccer is one of the most popular sports worldwide, which subsequently increases the number of injuries experienced by players. Furthermore, a large percentage of all anterior cruciate ligament injuries occur while playing soccer. In order to more clearly understand injury mechanisms, it is important to make the testing environment as real-life as possible. Inclusion of an external focus and secondary task, such as heading a soccer ball, may increase joint loading during landing. The purpose of this study was to investigate the effect of a forward heading motion on lower extremity kinetics and kinematics between sexes during a stop-jump task and a jump-heading task. METHODS: Ten male and ten female soccer players performed stop-jumps with no soccer ball present and jump-headings with a soccer ball present. Three-dimensional kinematics and kinetics were collected and analyzed during the landing. 2 × 2 mixed design analysis of variances (ANOVA) were performed to examine sex × jump task interactions and determine the main effects of sex and jump task. RESULTS: Results indicated jump-heading yields greater peak vertical ground reaction forces, an 8% increase in peak knee extension moments, a reduced initial knee flexion angle by approximately 5°, and an increased initial hip flexion angle by approximately 7°. Additionally, females exhibited 5.6° greater peak knee abduction angles compared to men, regardless of task. CONCLUSIONS: Inclusion of an overhead target may have distracted the athletes from focusing on frontal plane knee control when landing, and could potentially lead to increased ACL stress.

Age-dependence of semitendinosus tendon properties used for anterior cruciate ligament reconstruction differs in males and females.

BACKGROUND: The semitendinosus tendon is one of the most used autografts in anterior cruciate ligament reconstruction. Although recent evidence indicates that young patients, especially in females, may experience high rates of revision and residual instability, the reasons for the inferior outcomes in these patients remain unclear. To address this issue, we aimed to compare the mechanical properties of the semitendinosus tendon used for anterior cruciate ligament reconstruction in male and female patients of various ages. METHODS: The semitendinosus tendons harvested from 31 male and 29 female patients who underwent anterior cruciate ligament reconstruction surgery using the semitendinosus tendon autografts were used in this study. Using the distal part of the harvested semitendinosus tendon, the extent of cyclic loading-induced elongation (i.e., the extent of the increase in slack length) and the Young's modulus were measured during cyclic tensile testing. FINDINGS: Spearman correlation analyses revealed that the Young's modulus (|ρ| = 0.725, P < 0.001), but not elongation (|ρ| ≤ 0.036, P ≥ 0.351) positively correlated with the patient age in male tendon samples. In contrast, for female tendon samples, the elongation (|ρ| ≥ 0.415, P ≤ 0.025), but not the Young's modulus (|ρ| = 0.087, P = 0.655) negatively correlated with the patient age. INTERPRETATION: These results indicate that the semitendinosus tendon used for anterior cruciate ligament reconstruction in young male patients is compliant, whereas that in young female patients is susceptible to elongation induced by cyclic loading.

Muscle activation in the lower limb muscles in individuals with dynamic knee valgus during single-leg and overhead squats: a meta-analysis study.

BACKGROUND: Dynamic knee valgus (DKV) is a risk factor for non-contact anterior cruciate ligament (ACL) injuries. Understanding the changes in the electromyographic activity of the lower extremity muscles in individuals with DKV helps trainers design ACL injury prevention exercises. Therefore, the present meta-analysis aimed to investigate the muscle activation of the lower limb muscles in individuals with DKV during single-leg and overhead squats. METHODS: Articles with titles, abstracts, and full texts were searched and screened independently by two reviewers in the Web of Science, Scopus, PubMed, and Google Scholar databases, without restrictions on publication date and in English using specified keywords from their inception to January 5, 2024. The quality of articles was evaluated using a modified version of the Downs and Black quality checklist. This meta-analysis used mean difference (MD) to compare the muscle activity patterns between individual with DKV and healthy individuals. Heterogeneity was detected using I-square (I2) test. RESULTS: In total, four papers with 130 participants were included in the study. Evidence showed a significant difference between the DKV group and the healthy group regarding the activities of the adductor magnus (MD: 6.25, P < 0.001), vastus medialis (MD: 13.23, P = 0.002), vastus lateralis (MD: 11.71, P = 0.004), biceps femoris (MD: 3.06, P = 0.003), and tibialis anterior muscles (MD: 8.21, P = 0.02). Additionally, muscle activity in the DKV group was higher than that in the healthy group. CONCLUSIONS: This meta-analysis reveals distinct muscle activation patterns in individuals with dynamic knee valgus (DKV), with increased activity in key muscles suggesting compensatory responses. These findings underscore the need for targeted rehabilitation to address muscle imbalances and improve knee stability.

Registry-based cohort study comparing percentages of patients reaching PASS for knee function outcomes after revision ACLR compared to primary ACLR.

OBJECTIVES: Reaching the Patient-Acceptable Symptom State (PASS) threshold for the Knee injury and Osteoarthritis Outcome Score (KOOS) has previously been reported to successfully identify individuals experiencing clinical success after anterior cruciate ligament reconstruction (ACLR). Thus, the objectives of this study were to examine and compare the percentages of patients meeting PASS thresholds for the different KOOS subscales 1 year postoperatively after primary ACLR compared with revision ACLR (rACLR) and multiply revised ACLR (mrACLR), and second, to examine the predictors for reaching PASS for KOOS Quality of Life (QoL) and Function in Sport and Recreation (Sport/Rec) after mrACLR. DESIGN: Prospective observational registry study. SETTING: The data used in this study was obtained from the Swedish National Ligament Registry and collected between 2005 and 2020. PARTICIPANTS: The study sample was divided into three different groups: (1) primary ACLR, (2) rACLR and (3) mrACLR. Data on patient demographic, injury and surgical characteristics were obtained as well as mean 1-year postoperative scores for KOOS subscales and the per cent of patients meeting PASS for each subscale. Additionally, the predictors of reaching PASS for KOOS Sport/Rec, and QoL subscales were evaluated in patients undergoing mrACLR. RESULTS: Of the 22 928 patients included in the study, 1144 underwent rACLR and 36 underwent mrACLR. Across all KOOS subscales, the percentage of patients meeting PASS thresholds was statistically lower for rACLR compared with primary ACLR (KOOS Symptoms 22.5% vs 32.9%, KOOS Pain 84.9% vs 92.9%, KOOS Activities of Daily Living 23.5% vs 31.4%, KOOS Sport/Rec 26.3% vs 45.6%, KOOS QoL 26.9% vs 51.4%). Percentages of patients reaching PASS thresholds for all KOOS subscales were comparable between patients undergoing rACLR versus mrACLR. No predictive factors were found to be associated with reaching PASS for KOOS QoL and KOOS Sport/Rec 1 year postoperatively after mrACLR. CONCLUSION: Patients undergoing ACLR in the revision setting had lower rates of reaching acceptable symptom states for functional knee outcomes than those undergoing primary ACLR. LEVEL OF EVIDENCE: Prospective observational registry study, level of evidence II.

Video Analysis of Anterior Cruciate Ligament Injuries in National Basketball Association Athletes.

PURPOSE: Research surrounding the biomechanics and video analysis of anterior cruciate ligament (ACL) injuries at the professional level has emerged in recent years as a tool to screen athletes for potential biomechanical deficits. The purpose of this study was to analyze and discuss the most common mechanism, body position, and activity at the time of ACL injury among NBA players. METHODS: Anterior cruciate ligament injuries over 10 consecutive NBA seasons (2009-2010 to 2019-2020) were reviewed from publicly available sources. A 10-question survey was developed and utilized to analyze each video clip. These questions were divided into three categories: 1. contact mechanism, 2. activity at the time of injury, and 3. position of the involved lower extremity at the time of injury. Two reviewers analyzed the videos individually, and differing answers were resolved via consensus review, with a senior author arbitrating in the case of any discrepancies. RESULTS: Overall, 23 ACL ruptures were included. The most common injury mechanism was indirect contact with another player without knee contact (56.5%), and no patients had an ACL rupture as a result of direct knee contact with another player. The most common action at the time of injury was pivoting (47%), and the most common basketball action was dribbling (43.5%). Additionally, the vast majority of patients were injured while on offense (91.3%). The most common knee positions were early flexion (73.9%) and abduction (95.7%). The most common foot positions were abduction relative to the knee (82.6%), in eversion (73.9%), and dorsiflexion (56.5%). The most common hip position was early flexion (87%), and all hips were abducted (100%). CONCLUSION: Our study found that the majority of ACL ruptures occurred during offensive play and over half were secondary to contact with an opposing player (but without a direct blow to the injured knee), indicating that such perturbations may alter the kinematics of the players' movement. Additionally, a large majority of ACL injuries occurred while the hip was abducted with the knee in abduction relative to the hip and while the knee was in early flexion from 0° to 45°.

A hop testing alternative for functional performance following anterior cruciate ligament reconstruction.

The purpose of this work was to provide a simple method to determine reactive strength during the 6-meter timed hop test (6mTH) and evaluate its association with isokinetic peak torque in patients following anterior cruciate ligament reconstruction (ACLR). Twenty-nine ACLR patients who were at least four months from surgery were included in this analysis. Participants were brought into the laboratory on one occasion to complete functional testing. Quadriceps and hamstring isokinetic testing was completed bilaterally at 60, 180, and 300 deg∙s-1, using extension peak torque from each speed as the outcome measure. The 6mTH was completed bilaterally using a marker-based motion capture system, and reactive strength ratio (RSR) was calculated from the vertical velocity of the pelvis during the test. An adjustment in RSR was made using the velocity of the 6mTH test to account for different strategies employed across participants. Repeated measures correlations were used to determine associations among isokinetic and hop testing variables. A two-way mixed analysis of variance was used to determine differences in isokinetic and hop testing variables between operated and non-operated legs and across male and female participants. Moderate positive associations were found between RSR (and adjusted RSR) and isokinetic peak torque at all speeds (r = .527 to .577). Mean comparisons showed significant main effects for leg and sex. Patients showed significant deficits in their operated versus non-operated legs in all isokinetic and hop testing variables, yet only isokinetic peak torque and timed hop time showed significant differences across male and female groups. Preliminary results are promising but further development is needed to validate other accessible technologies available to calculate reactive strength during functional testing after ACLR. Pending these developments, the effects of movement strategies, demographics, and levels of participation on RSR can then be explored to translate this simple method to clinical environments.

Comparison of histopathological and biomechanical changes of ligamentum mucosum in patients with anterior cruciate ligament rupture.

OBJECTIVES: The aim of this study was to identify the biomechanical and histopathological changes of ligamentum mucosum (LM) in patients with intact versus ruptured anterior cruciate ligament (ACL). PATIENTS AND METHODS: A total of 67 patients (45 males, 22 females; mean age: 33.2±7.9 years; range, 18 to 45 years) who underwent arthroscopic knee surgery for intraarticular pathologies between July 2022 and January 2023 were prospectively analyzed. The patients with LM were divided into two groups as the ACL intact group (n=31) and ACL ruptured group (n=36). Biomechanical tests and histopathological examinations were performed in all LM patients. RESULTS: Age and body mass index distributions were similar between the groups (p>0.05). Peak force values of the LM in the ACL ruptured group were significantly higher than the ACL intact group (p=0.037). No significant difference was found between the groups in terms of collagen index (p=0.103) and fibroblast count (p=0.821). CONCLUSION: The peak force values of the LM were significantly higher in the ACL ruptured group as compared to the ACL intact group, which is probably due to the adaptation of LM in patients with ACL rupture against increased deforming forces to maintain knee stability.

Effect of ball positions on trunk, hip, knee, and ankle joint kinematics and kinetics during a spike jump in volleyball.

BACKGROUND: Anterior cruciate ligament injuries are serious conditions encountered in volleyball players and occur frequently during spike jump landings. During spike jumps, the lower limb kinematics and kinetics during landing may be altered in relation to the ball position. RESEARCH QUESTION: Does the ball position have an effect on lower-limb kinematics and kinetics during spike jumps? METHODS: We measured the lower limb kinematics and kinetics of 20 healthy female college volleyball athletes during a spike jump using a three-dimensional motion analysis system. The ball positions were set to normal, dominant, and non-dominant positions. A repeated analysis of variance was used to compare the lower limb kinematics and kinetics at the initial contact and the maximum knee flexion during jump landing. Additionally, statistical parametric mapping analysis was used to analyze changes over time during the spike jumps. RESULTS: At the initial contact of the spike jump landing, the knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment when the ball was set at the non-dominant position increased compared to those at the dominant position. Statistical parametric mapping analysis showed no significant change in knee valgus angle and moment of jump landing. CONCLUSION: Knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment increased with the non-dominant position; furthermore, the risk of ACL injury may also be increased. SIGNIFICANCE: The posture at ball impact may influence the landing kinematics and kinetics. Therefore, it is necessary to pay close attention to movements during and prior to landing.

The effects of fatigue on the relationship between ankle angle at initial contact and the knee and hip joints in landing: Assessing the risk of ACL injury.

BACKGROUND: Anterior cruciate ligament (ACL) injuries may correlate with lower limb angles and biomechanical factors in both dominant and non-dominant legs at initial contact (IC) post-landing. This study aims to investigate the correlation between ankle angles in three axes at IC and knee and hip joint angles during post-spike landings in professional volleyball players, both pre- and post-fatigue induction. RESEARCH QUESTION: To what extent does fatigue influence lower limb joint angles, and what is the relationship between ankle joint angles and hip and knee angles at IC during the landing phase following a volleyball spike? METHODS: Under conditions involving the peripheral fatiguing protocol, the lower limb joint angles at IC following post-spike landings were measured in 28 professional male volleyball players aged between 19 and 28 years, who executed the Bosco fatigue protocol both before and after inducing fatigue. A paired t-test was utilized to compare the joint angles pre- and post-fatigue in both dominant and non-dominant legs. Furthermore, Pearson's correlation test was conducted to explore the relationship between ankle angles at IC and the corresponding knee and hip joint angles. RESULTS: The findings of the study revealed that fatigue significantly increased hip external rotation and decreased knee joint flexion and external rotation in both the dominant and non-dominant legs (p < 0.05). Additionally, correlation analysis demonstrated that the ankle joint's positioning in the frontal and horizontal planes was significantly associated with hip flexion and external rotation at the IC, as well as with knee flexion and rotation (0.40 < r < 0.80). CONCLUSION: Fatigue increased hip external rotation and ankle internal rotation, weakening the correlation between these joints while strengthening the ankle-knee relationship, indicating a reduced hip control in jumps. This suggests a heightened ACL injury risk in the dominant leg due to the weakened ankle-hip connection, contrasting with the non-dominant leg.

Strength and clinical test combinations enhance predictions of sagittal and frontal plane biomechanics in single-leg landing.

OBJECTIVES: To determine whether clinical screening tests can predict lower limb joint kinematics and kinetics outcomes eliciting anterior cruciate ligament (ACL) injury risk in single-leg landings. DESIGN: Cross-sectional study. SETTING: Laboratory research. PARTICIPANTS: Twenty-six professional male futsal athletes. MAIN OUTCOME MEASURES: Participants completed the Modified Star Excursion Balance Test (mSEBT), Lateral Step Down (LSD), Lunge, Hop tests, and isometric strength tests for clinical screening of lower extremity injury risk and performed single-leg landings to assess lower extremity 3D kinematics and kinetics outcomes. RESULTS: mSEBT, LSD, and isometric strength were the more important tests when constructing the prediction models. The predictive power of clinical tests for screening injury risk significantly increases when combined with strength measurements (p = 0.005, f2 = 0.595). We discerned 11 biomechanical predictions, six explicitly related to the sagittal plane's biomechanics. Some predictions were leg-dependent, with muscle strength tests predominantly predicting biomechanical outcomes of the preferred leg. CONCLUSION: Combining clinical screening tests with strength measures enhances ACL injury risk factors prediction during single-leg landings. Clustering at least two tests improves prediction accuracy, aiding injury prevention planning and decision-making.

Contribution of ankle motion pattern during landing to reduce the knee-related injury risk.

BACKGROUND: Single-leg landing (SL) is an essential technique in sports such as basketball, soccer, and volleyball, which is often associated with a high risk of knee-related injury. The ankle motion pattern plays a crucial role in absorbing the load shocks during SL, but the effect on the knee joint is not yet clear. This work aims to explore the effects of different ankle plantarflexion angles during SL on the risk of knee-related injury. METHODS: Thirty healthy male subjects were recruited to perform SL biomechanics tests, and one standard subject was selected to develop the finite element model of foot-ankle-knee integration. The joint impact force was used to evaluate the impact loads on the knee at various landing angles. The internal load forces (musculoskeletal modeling) and stress (finite element analysis) around the knee joint were simulated and calculated to evaluate the risk of knee-related injury during SL. To more realistically revert and simulate the anterior cruciate ligament (ACL) injury mechanics, we developed a knee musculoskeletal model that reverts the ACL ligament to a nonlinear short-term viscoelastic mechanical mechanism (strain rate-dependent) generated by the dense connective tissue as a function of strain. RESULTS: As the ankle plantarflexion angle increased during landing, both the peak knee vertical impact force (p = 0.001) and ACL force (p = 0.001) decreased significantly. The maximum von Mises stress of ACL, meniscus, and femoral cartilage decreased as the ankle plantarflexion angle increased. The overall range of variation in ACL stress was small and was mainly distributed in the femoral and tibial attachment regions, as well as in the mid-lateral region. CONCLUSION: The current findings revealed that the use of larger ankle plantarflexion angles during landing may be an effective solution to reduce knee impact load and the risk of rupture of the medial femoral attachment area in the ACL. The findings of this study have the potential to offer novel perspectives in the optimized application of landing strategies, thus giving crucial theoretical backing for decreasing the risk of knee-related injury.